Throughout recent years, implantable medical apparatus have been used more and more frequently to diagnose and treat medical conditions. These implantable apparatus require a power source to function. External power sources may be used in some circumstances, such as when the patient wears a battery pack outside of his body that powers an apparatus implanted in his body. Such external power sources can be cumbersome and inconvenient. Therefore, many implantable medical apparatus use energy storage devices that are themselves implantable with the medical apparatus.
These implantable energy storage devices, however, have some drawbacks. For example, it is generally difficult to replace an expired energy storage device because a physically-intrusive procedure is required. Also, because implantable medical apparatus are generally required to be quite small, implantable energy storage devices must also be much smaller than external energy storage devices. Therefore, implantable energy storage devices need to be designed to account for the desired lifetime of the implantable medical apparatus, to provide the necessary power over that desired lifetime, and to fit within the implantable apparatus. Such design specifications generally require extended design, development, testing, and production cycles—in some cases, it may take more than five years from the determination of initial design specifications for an implantable energy storage device ultimately to go into production. Some factors that lead to long product development cycles are designing, testing, and refining (i) the chemistry for the electrodes in the energy storage device, (ii) the mechanical assembly of the energy storage device (e.g., overall shape of the energy storage device, placement of the electrodes, connection of the electrodes to the terminals, etc.), and (iii) the manufacturing and mass-production processes for the energy storage device.
For example, the connections formed between the terminals of the energy storage device and the electrodes typically are complex. Furthermore, the space required to house these connections reduces the energy density of the energy storage device (i.e., the more space required for the connections, the less space available for the active elements of the energy storage device such as the electrodes). The research, development, and testing that is involved in producing an energy storage device is thus vital to achieving an efficient design of the energy storage device. Such research, development, and testing of a new energy storage device configuration can be lengthy and expensive.
It is therefore desirable to reduce these product development cycles in order to allow an energy storage device for the implantable medical apparatus to become available more quickly. In order to reduce these product development cycles, it is important to reduce the time associated with the different steps in the cycle. Creating a modular implantable energy storage device in which the chemistry, mechanical assembly, and/or production processes have already been proven, and wherein only small changes are required to adapt the modular device to a particular application, will result in substantially reduced product development cycle times.